Discharge device



Dec. 16, 1941. H. J. sPANNER ETAL DISCHARGE DEVICE Filed 061'.. 23, 1956 3 Sheets-Sheet l ATTORNEYS H. J. SPANNER ET AL DISCHARGE DEVICE Filed Oct. 23, 1956 3 Sheets-Sheet 2 mvEN-rons Dec. 16, 1941.

H. J. sPANNER ET AL DISCHARGE DEVICE Filed Oct. 25, 1936 3 Sheets-Sheet 3 INVENTCRS A AfA/VJ JSP/INN Patented Dec. 16, 1941 DISCHARGE DEVICE Bans J. Spanner and Werner Lucas, Berlin, Germany; said Spanner assignor of his right to General Electric Company,

New York a corporation of Application october-2s, 1936, serial No. manu In Germany November 21,1931

17 Claims. V(Cl. 176-122) y danger from handlingto which the devices would This invention relates to electrical discharge devices; More particularly the invention relates to such devices adapted for standardized production and commercial use under varying conditions such, for example, as those encountered in general illumination service, or for ultra violet radiation burners.

In prior applications of Hans J. Spanner alone and in conjunction with. others particularly Serial No. 351,368, filed March 30, 1929, Serial No. 387,986, filed August 23, 1929, Serial Nos. 397,427, 397,428 and 397,429 all filed October 4, 1929, Serial No. 400,805, filed October 19, 1929, Serial No. 558,148', filed August 19, 1931, Serial No. 643,502, led November 19, 1932, Serial N0. 714,949, led. March 10, 1934, Serial No.,744,206, led September 15, 1934 and Serial No. 51.390, filed September 25, 1935 and in the applications of Edmund Germer, Serial No. 500,346, filed December 15, 1930 and Serial No. 60,774, filed January 25, 1936, and in the applications led herewith, there have been described and claimed a type of discharge device adapted particularly for illuminating lamps and ultra violet burners for operation'froxn ordinary low voltage distribution line, and various improvements and special features of such devices.

These'inventions and improvements disclosed in the said prior applications have made practicable the design of high efliciency discharge devices especially for illumination and ultra violet purposes which may be adapted to widely varying conditions and requirements.

It is an object of the present invention to so improve upon such devices that they may be manufactured in standard designs and sold for general purposes and use under varying condltions. f Another object of the invention is to provide devices of this character adapted to utilization in standard outlet sockets and connectors without injury to such sockets and connectors or impairment of the emciency of the discharge device. Another object of the invention is to assure the quick-starting of such devices even without the necessity for extraneous startingv devices in the circuits by which the devices are operated.

Another object of the invention is to provide a device capable of burning in horizontal as well .as in vertical position without serious injury to the walls of the device.

be subjected in transportation anduse.

In the accompanying drawings we have shown, and in the following specification have described a preferred embodiment of our invention by which these objects are achieved together with various modifications thereof and alternatives. It. is to be understood. however, that the drawings and descriptions are not intended to be exhaustive nor limiting of the invention, but on the contrary are given for the purposes of explaining and illustrating the invention and the best Ways of embodying it in practical construction, and of explaining the principles of the invention so clearly that others skilled in the art may, without dimculty, embody lthe invention in numerous other forms each as may be best suited to the conditions and requirements of a particular use.

In the drawings:

Fig. 1 is a view in longitudinal section of a lamp embodying our invention;

Fig. 2 is a view similar to Fig. 1, but of a modifled form of thel lamp;

Fig. 3 is a view in cross-section through a tube similar to those illustrated in Figs. 1 and 2 showing an electrode mounting;

Fig. 4 is a plan view of the electrode and its mounting as used in the embodiments shown in Figs. 1 and 2.

Fig. 5 is a View in side elevation of another embodiment of our invention;

Figs. 6 and 7 are views in longitudinal and cross-section respectively on a greatly enlarged scale of a control switch adapted for use with a lamp as shown, for example, in Figs. 1, 2, 5 or 8;

Fig. 8 is a view in axial section of another lamp embodying our invention; and

Fig. 9 is a diagrammatic view of a circuit adapted to assure starting of the lamps on low voltage lines,

Referring specifically to Figs. 1 and 2, we have shown there two forms of tubes adapted for general illumination purposes and for operation from a 110-120 volt line with an operating current of about 5 amperes immediately after starting and reducing, with evaporation of mercury or other vaporizable materials, to a current ofabout 3.4 amperes during normal operation. Fig. 2 shows in approximately full scale a lamp adapted for operation, e. g., from 110 volt-150 volt supply.

' In Fig. l, accurate scale representation has been Another' object of the invention is to provide such a device in which all delicate and dangerous sacriiiced to permit clearer representation of the parts.

parts of the lamp are enclosed so as to avoid specically in Fig. 4. These may consist, for example, of about 40 wires of about 0.25 millimeter diameter, e. g., of pure nickel or tungsten, tightly twisted or interwoven into a stranded wire which is in turn wound into three tight coils as shown. These coils constitute the electrode proper I I, which, after suitable activation serves to carry the discharge.

nation with the metal of the supporting structure, e. g., nickel or tungsten. To effect this result the supporting metal'structure may be covered and impregnated with the activation material, and the electrode, after being sealed into the tube, subjected to a high temperature treatment near the meltingpoint of nickel and eventually to a treatment by direct action of the discharge, e. g., in an inert gas or mercury vapor, until the desired reduction is attained. This treatment is not a part of the present invention, but is more fully described and claimed in our co-pending applications and, therefore, need not be further elaborated upon here.

A second important consideration in the starting of these lamps is the provision of a gaseous filling at suitable pressure. 'Ihis also is a distinct invention described and claimed in a copending application. In a tube of the form and dimensions shown, and designed for operation from 110 to 150 volt lines, this gas filling may consist of argon at a pressure of about 8 to14 millimeters mercury column.

These electrodes, which are adapted to become incandescent by action of the discharge without any additional heating means are not claimed per se in the present application and are more fully described and claimed in our oo-pending applications. These electrodes, however, although not essential to the present invention in its broadest aspect, are particularly advantageous because they eliminate the necessity for special heaterl connections and make possible a simple 'and rugged construction more suitable for the standardized production and commercial use, which is one object of this application.

In use with alternating current, preferably at least two such electrodes are fitted in the tube, and they alternately become cathode and anode. When direct current is used only one electrode of such self-heating type is necessaryand the anode asis well-understood can be made of nondisintegrating material, It is advantageous with direct current to make the anode of larger dimensionsV than the cathode.

The ends of the coils constituting the electrode I-I are welded to the short-circuiting bow I2, which is made of a single piece of refractory metal, such as nickel or tungsten, heavy enough to support the electrode from the lead-in wire and to carry the induced currents resulting from the high frequency bombardment used to produce the activation of the'electrodes, without excessive resistance or overheating in the bow I2- itself. For example, this bow I2 may be made of nickel wire 3 millimeters in diameter flattened 75 to a thickness of about 11/2 millimeters. The ends of the bow are welded to the ends of the wires in the electrodes proper II in order to give good electrical contact and mechanical support.

The bow I2 is also welded to the lead-in or support wire I3 or I4 at thel side opposite to the electrode proper.

Before being sealed in, the emitting part II of the electrode is ,covered with the activation material, e. g., a layer of nely ground barium oxide advantageously mixed with other refractory oxides, e. g., calcium oxide, beryllium oxide, magnesium oxide, zirconium oxide, etc., made into a viscous mass with distilled water. This mass is worked into the interstices of the electrodes and the electrodes when thus treated are preferably kept away from contact with air until sealed into the tube I5.

Although the particular construction shown is not essential to certain features of our invention in their broad aspect, we have found-it very advantageous to mount one of the electrodes on a wire I3 which is adapted to carry the discharge current to the electrode and is sufficiently long to extend'from the electrode to the opposite end of the tube and out through the wall of the tube, to which it is sealed as shown in the drawings. In order to avoid any danger of this wire short-circuiting the discharge, it is advantageously insulated throughout its length, e. g., by a glass tube I6 which is fused at one end to the wall of the tube I5 and extends along the wire I3 substantially -to its electrode.

In the case illustrated in Fig. 1, a second support wire I'I also welded to the bow I2 extends beyond the electrode to the end of the tube I5 where it engages in a depression I8 in the wall of the tube and preferably is held by fusion of the glass wall of the tube thereto.

The wire I1 may be omitted, as shown for example in Fig. 2, and the entire stress of supporting the electrodes carried directly by the wire I3 and its surrounding tube I6; or, as shown in Fig. 3, the bow I2a may be designed substantially to iit within the end of the tube I5; and in this case the bow 12a is preferably fresilient so as to press against the walls of the tube and thereby to support itself and the electrode II directly against the tube. It is not essential, however, that the bow I2a be directly in contact with the tube, and it may be made substantially rigid and spaced from the tube so as to allow for differences in thermal expansion, but sufiiciently close to avoid any danger of crashing against the side of the tube. y

The electrode support wire I 4 need not be insulated and may pass directly from the seal to the bow I2l as shown, for example, in the drawings. i

As shown in the drawings, the gia-ss tube I6 carries ametal band I9 which is in a capacitative relation to the lead wire I3, but is insulated therefrom by the dielectric tube I3. 'Ihis metal band I9, or the band I9a in Fig. 2, has a part extended near the lower electrode Il to provide an auxiliary lelectrode for an initial capacitative or corona discharge. In the case illustrated in Figl, this auxliairy electrode consists of a band of wire mesh III surrounding the insulating tube Il and extending toward the. electrode II. This auxiliary electrode is connected to the band I9 by a metaly strip 2| which is integral with theband I9 and is welded to the mesh 20.

In the embodiment illustrated in Fig. 2, a similar function is served by the integral portion 20a turned back from the band ISa. Capacity between the electrodes may also be provided by a strip on the outside of the tube. This may be in addition to or instead of the capacity members already described inside of the tube, particularly in the case where the connection to the upper electrode is sealed through the upper end of the tube and brought back on the outside of the tube instead of the inside as shown. In the drawings we have shown such a capacity member as a conductive film 22, e. g., of reecting metal; and in order that this may come as close as possible to the electrode and also that the temperature in the end of the tube I may remain as high as possible, the tube I5 around the electrode is made smaller than the principal portion of the tube in which the luminous arc burns.

In the case shown in Fig. 2, the layer 22 is connected to the lead wire I3 for the electrode at the opposite end of the tube so that a capacitative discharge may occur between the electrode I I and the side of the tube in parallel to that between the electrodes II and a. This capacity furthermore, in conjunction with a choke coil, such as is commonly used Yin series with such lamps to ballast the discharge, results in a better starting impulse and a more certain starting from the low voltage electrical supply line.

In the case illustrated in Fig. 1, the layer 22 Vis connected to the adjacent electrode, and in this case the capacity is between the layer 22 and the surrounding metal sleeve 23, which will be `more fully discussed later. Inthis case the capacity is in parallel with the discharge and its eect is primarily that of improving the starting impulse especially in conjunction with a reactance, as already referred to.

A startinggas, e. g., one of the rare gases at a pressure near or above its pressure of minimum breakdown potential, and advantageously also a vaporizable material are provided within the tube I5. The vaporizable material is advantageously supplied in amount measured to produce, when completely evaporated, a. vapor pressure such that the voltage which, in the rst moment after starting has dropped to a very low value, is again increased almost to the starting voltage or even above; and the discharge, which in the rst ly fills the interior of the tube, is constricted into an intense luminous cord very-much narrower than the diameter of thetube. It is,ofk

tube should be so made that there will be no places below the condensation temperature of the 4metals at their operating pressures and advantageously no places at much below the mean temperature of the interior of the tube.

The shape of the tube I5 shownV in the drawings is well adapted to accomplish these results.

' The glass used in this tube may be any which'is permeable to the desired radiation, which is sufficiently refractory to withstand the temperatures to which it is exposed from the arc, and

ymoments after starting is diffuse and substantialby Schott of Jena, are suitable for this purpose and `can be sealed directly to a tungsten wire used for the lead-in wires I3 and I4.

The conductive layer 22 on the end of the tube may bemade by applying a colloidal suspension of graphite and water directly on the glass, e. g., the so called aquadag, and over this may be applied metal leaf or foil or an electro-deposit of metal. The conductive layer thus formed is carried down over the projecting seal to one of the lead-in wires I3, I4.

An electrical and thermal insulating layer 24,

preferably of asbestos or other resilient com-` pressible material adapted to serve also as a cushion between the metal sleeve 23 and the end of the tube I5, is provided over the reflecting conductive layer 22V; and lthus a condenser is established between the layer 22 and the metal sleeve 23 in parallel with the discharge. This capacity in the structure of the tube, with or without additional capacity, and especially when combined with a reactance, such as a choke .coil in series, assists greatly in starting the lamp and operation on A. C. supply; and this is particularly the case if the capacity and the ballasting device are proportioned so that resonance, especially overbalancing or oscillation resonances (Kippresonancen) as from relaxation oscillations, are formed with the alternating current supply. We have found, however, that continued resonance is undesirable in the operation of the tube; and if an additional capacity is used to give resonance, rit should be switched into the circuit only for starting and switched ofi again as soon as the discharge is started.

It is an advantage of the relaxation oscillations that they are particularly rich in harmonics, both above and below the frequency of the supply line,

and thus resonance is easily produced without excessively large condensers. Furthermore, such resonance, being dependent upon the oscillations produced by the intermittent discharge, ceases as'soon as the main discharge is established and, therefore, with a properly designed circuit, extraneous switching devices are unnecessary.

An auxiliary discharge, e. g., to the auxiliary electrode 20 or to the wall of the tube I5 beneath the capacity layer 22 or to a resistance connected auxiliary electrode can be used in connection with the production of oscillations, and the additional capacity provided by the layer 22 and the sleeve 23 and/or between the layer 22 and the electrode II may serve at least in part which can be sealed, either directly or through intermediate sealing compounds, e. g., other glasses to the lead-in wires I3 and I4, or it may be silica. We have found that the hard borosilicate glasses, e. g., that known as Pyrex made by CorningGlass Works .and sold under the designation 702P and the glass known as Uviol glass made as the parallel capacity. The capacity connected auxiliary electrode combines particularly well with a relaxation oscillation circuit which is resonant to higher frequencies because such frequencies pass with less impedance through the capacitative auxiliary circuit and more readily ionize the gas.

In Fig. 9, is shown diagrammatically a circuit adapted to start the discharge by a resonance effect. The discharge tube is indicated at lfm: and its electrodes at llc. An auxiliary electrode is indicated at 20c and connected to the lead wire I 4c throughl an impedance I9c, which may be resistance or capacitance or even inductance,

but this auxiliary is not essential. A ballasting impedance 55 is shown as an inductance, and a condenser 56 is connected in parallel across the electrodes forming a capacitative shunt around the discharge path, a relay 51 in this shunt is adapted to be .opened by the discharge current so as to disconnect the condenser.

In this circuit the condenser may be proportioned with respect to the rst of the circuit so as to produce resonance at the frequency of the A. C. supply voltage or the circuit may be designed to give relaxtion oscillations and to be resonant to a higher harmonic of the supply voltage which is produced by the relaxation oscillation resonance in the circuit, but as soon as starting occurs the shunt is opened by the relay 51 and thus the tube I5 is protected against the deteriorating effect of prolonged resonance.

For actual technical use it is of advantage to t the lighting tubes in sockets adapted for standard incandescent lamps or so-called strip lamps (somt lamps). With this end in view We have shown in Fig. 1 a lamp connected to a base 25 of standard Ediswan design; and, in order that this base 25 will not be overheated by the lamp, or vice versa will not excessively cool the end of the lamp, I have provided between the base 25 and the tube I5 a sleeve 23 which at one end is secured to the shell of the base 25 and at the other end is secured to the end of the tube I5. In the example shown this sleeve is of metal integral with or welded or soldered to the base and secured to the tube I5 by being crimped thereover and clamped by means of the Wires 26 and 21. Holes 28 and 29 arranged in circumferential series and staggered with respect to one another form a themnal barrier to resist the transfer of heat from the tube I5 to the base 25. 'I'his sleeve 23 also surrounds and serves to protect the electrical connections 3I and 32 from the lead wires I3 and I4 respectively to the base.

Although we have referred particularly to the capacity effect between the shell 23 and the conductive layer 22, as shown in Fig. l, this relationship is not essential to my invention in its broader aspects; and, for example in the case illustrated in Fig. 2, the shell is applied directly to the layer 22; or the layer 22 may be omitted entirely; and the sleeve 23 obviously could be made of insulating material instead oil conducting material. Thus, for example, if this tube 'were of glass it could be fused directly to the glass of the envelope I5.

In the use of the device, the tube with its base 25 may be screwed into an ordinary Ediswan socket connected in series with a suitable ballasting device, e. g., a choke coil or high reactance or current limiting transformer, from a current supply line, e. g., at 110 volts.

Upon closing the circuit, a voltage is impressed upon the discharge path between the electrodes II and also, through the capacity I3, I9 and the electrode 20, is impressed upon the shorter path between the auxiliary electrode 20 and the adjacent principal electrode II. Between these two, a. capacitative or corona. discharge may occur, which. serves to ionize the gas, while the charge imposed upon the capacity member I9 or the current lead wire I3 serves to eliminate any static charge in the path between the main electrodes which otherwise might throttle or block the passage of the discharge. Accordingly, as soon as the gas is sufliciently ionized the discharge begins between the principal electrodes. At first this discharge loccurs as a glow-discharge between cold electrodes. Almost at once, however, the fine wires of which the electrode is made begin to be heated by the discharge; and as they reach a glowing temperature the discharge is converted into an arc. With this arc burning in the low pressure atmosphere existing at that time within the tube I5, there is a minimum voltage drop in the lamp, e. g., of around 15 to 20 volts, and consequently a. maximum current, e. g., o1' around 5 amperes. With this heavy loading, the tube is quickly heated until the mercury or other vaporizable supply is evaporated.

During this period the voltage drop in the tube increases, due to the increase in pressure by evaporation of mercury and/or other metal, until, during normal operation, the lamp burns with a voltage between the electrodes of v. and a current of 3.4 amperes. In this nal condition the arc appears as an intense luminous cord extending between the electrodes and of diameter very much less than that of the tube. The heat of this luminous cord is so intense that if it were to. impinge upon the wall of the tube I 5 or upon the insulating tube I6 they might be quickly destroyed, or at least so far softened as to cause a failure of the lamp. With the lamp burning in vertical position, the danger oi the arc cord impinging upon the wall is relatively slight; butI if the lamp isburned in horizontal position, convection currents within the lamp tend to draw it upward into an arcuate form between the electrodes. The construction of the lamp, as shown especially in Fig. 2, is designed to correct this tendency. In this case, as will be observed from the drawing, the electrodes I I are positioned substantially eccentrically of the tube and on the opposite side of the axis of the tube from the current lead wire I3; and furthermore the central portion of the tube is of'enlarged diameter such that any bending of the arc which may occur can be accommodated without injury to the tube.

When the lamp is burned in horizontal position with the lead wire I3 uppermost the convection currents in the lamp still tend to lift the arc toward the upper wall of the tube, but this tendency is opposed by the repulsion resulting from the opposite magnetic effects induced around the current flowing through the wire I3 and the current owing through the arc itself; and thus the arc is driven back downward against the force of the convection current. Even this, however, might be insuflicient in a tube of small diameter. We have, therefore, increased the diameter near the center of the tube, shown in the drawing, which permits the arc to rise abov'e the level of the electrodes without impinging upon the parts which might'be damaged thereby.

Merely to increase the diameter of the tube, however, would, if the electrodeswere at the axis, result in an excessive heat lossA due to the increased area of the tube. In the present lamp, therefore, the electrodes are placed on the opposite side of the axis of the tube from the lead wire I3, and thus ample space is provided for the Aarc to rise above the electrodes without injuring any part of the tube.

When the lamp burns in vertical position, the opposed magnetic effect may cause it`to assume some curvature toward the opposite side, but this lamp'is, of course, decreased; and, since the magnetic. effects are dependent upon the current, therevis a decrease in the tendency of the lead the final vapor pressure in the wire I3 to repel the arc. Similarly also, unless K lamp is increased, the distance between the electrodeswould have to be increased with increased voltage; and this in turn would increase the height to which vthe arc would rise with a given curvature. It is importanttherefore, to keep the lamp as short as possible and the current of the arc as heavy as possible.

It will be readily understood from general principles of electromagnetism that the magnetic effect can be increased by increasing the number of longitudinal turns of the current lead wire around the lamp. In general, however, it is not desirable to rely too greatly upon the electromagnetic eiect, since with the lamp in upright.

position the electro-magnetic opposition on the one side and attraction on the other side might draw the arc against the opposite wall. It is preferable, therefore, to combine the partial correction by the electro-magnetic e'iect of the lead wire with the enlarging of vthe arc portion of the tube and the eccentricity of the electrodes, as shown particularly in Fig. 2.

Since the several features, of magnetic repulsion, eccentric positioning of the electrodes and the relation of the distance between the electrodes to the distance of their common axis from the upper wall of the tube, cooperate to produce the desired positioning of the constricted luminous cord of the arc, the extent to which each of these expedients is used will depend, to some extent at least upon the extent to which the others are utilized. In general, however, it may be said that for lamps of ordinary size, e. g., from 100 to 500 watts, a ratio of distance between the electrodes to the distance between their common axis and the upper wall of the tube should be less than and preferably less than 5, the greater values being permissible where more highly refractory glass or silica is used or where stronger magnetic repulsion is used, and the lesser values being required where magnetic repulsion is not used or where the current loading is small or the lead wire I3 is outside of the tube I5, and especially if it is at a substantial distance from the wall of the tube. Simllarly, except for the higher wattages and with the current lead positioned. so as to give strong magnetic repulsion, it is ordinarily more satisfactory to use less than 150 volts for such lamps which are to be burned in horizontal position; and, since for reasons of operation and particularly starting it is ordinarily necessary that the arc voltage should be at least about '75 volts, I prefer to use a lamp designed for operation direct from a 110 volt commercial supply line, e. g., vwith a choke coil in series.

The wattage of the lamp is important both because it determines to some extent at least the area of the tube and therefore its diameter, and also because with greater wattage there is greater heating in the arc and therefore more tendency for it to arch up due to convection currents.

Inasmuch as such a lamp when burned in horizontal position should have the lead wire from the outer electrode at the top of the tube, it is advantageous to have some provisions for assuring this position. This may be done by using an unsymmetrical connector base; or, with an Ediswan base as shown in the drawings, a mercury switch, e. g., as shown in Figs. 6 and '1 will protect against improper operation. The mershown is designed to be cury switch there 23 or the base 25 or mounted within the sleeve vthe tube I5 and otherwise suitably attached to the lamp so that it will always remain in the same relation to the tube I5. This switch comprises a tube 40 of glass or other insulating material having two contact wires sealed through one end, e. g., by the press seal 4I, and extending to the opposite end as shown in Fig. and 43 form cups into which the mercury supply 44 within the tube may collect around the contact wires 45 and 46.' Between the ends 42 and 43 the wires extend close to the bottom of the tube 40, e. g., as shown in Fig. 7. The tube 40 is oriented to the tube I5 with ends 4 and 43 pointed in the same directions as the ends of the wires 45 and 46 lying along the side opposite to the side of the tube I5 Aalong which thelead wire I3 passes. I5 is positioned in upright position regardless of which end is uppermost the circuit of the lamp will be closed by the mercury pool lying in one end of the tube between the contact wires 45 and 46. Similarly, if the tube is in horizontal position with the lead wire I3 uppermost the mercury pool will' lie in the bottom of the tube and over the wires 45, 46 as shown in Fig. '7. In any other position, however, the mercury pool will lie in the enlarged portions of the tube 40'away from one or both of the wires 45, 46; and, therefore, the circuit of the lamp will remain open and the lamp cannot be operated s until it is put into a position in which no injury to the lamp will occur. If the construction of the lamp (e. g., the heat transfer capacity of the sleeve 23), should be such as to require that one end be always uppermost when the lamp is burned in vertical position, the wires 45-46 may be made shorter so as to fall short of the mercury pool in the opposite end of the tube 40.

In order to avoid arcing between the electrodes, the tube 40 is preferably` filled with a fluid in addition to the mercury which has a high breakdown voltage and is, therefore, adapted to quench any arc which might tend to form between the mercury and the contact wires 45, 46.

We have already referred to the possibility of having the current lead to the further electrode pa'ssvalong the outside rather than the inside of the tube I5. This we have illustrated in Fig. 5 in which the strip 50 made of metal sheeting, strip or wire is connected at one end to the lead wire IIb sealed through the upper end of the tube I5b and is brought back along the outside surface of the tube. Strip 50 in this case, like the wire I3 in the case of Figs.v1 and 2, serves as a capacity member and a magnetic repulsion means, as well as to lead the current to the outer electrode. In order to increase the capacity effect and to bring it as close as possible to the wall of the tube, a conductive layer 5I is deposited directly on the surface of the tube. This may be, for example, a layer of graphite deposited as a water suspension of graphite, e. g., such as is commonly knownA as aquadag, or a chemically and/or electrically deposited metal, or a strip of metal leaf or foil may be used so as to provide a high reflecting surface, thereby avoiding loss of light efficiency which might occur to some extent with the graphite. Also the exterior strip, acting at the same time as a reflector, can consist of silver, or chromium, or chromium plated metal. The quality of absorbing and holding radiant energy as heat is an advantage of the graphite layer when used on the pole vessel for the layer 22.

It is an advantage of this extended layer in 6. Each of the ends 42` Thus if the tube l intimate contact with the surface of the glass that it reduces the danger of injury to the glass by electrolysis or puncturing when a starting potential is imposed upon the glass while still very hot. Such danger might exist if only the relatively heavy lead connection 50 were in actual contact with the glass of the tube, since it could contact only at occasional points along its length, and in that case the electrical charge would be concentrated at the points of contact instead of being distributed, as in the case of the capacitative layer applied directly and in intimate contact on the surface of the glass.

If the current lead is returned outside of the tube in this way, it may advantageously be insulated, e. g., by enameling or by use of a glass jacket or otherwise. The base connection sleeve 23 may, of course, be similarly insulated.

The lamp shown in Fig. 8 is similar in construction and operation to that shown in Fig. 1, with certain obvious exceptions. In this case instead of mounting the tube |50 directly upon the connector base 25o, a protective jacket 23c is provided in which the tube ic is mounted by means of the spring 36 and the resilient twisted Wires 31. The connecting wire 32e between the connector base 25o and the lead-in wire Mc to the lower electrode llc serves also to hold the inner tube l5c in position within the jacket 23e.

In this case the electrodes Hc are in the form of shallow cups of refractory metal nested or lled with wire mesh or otherwise provided with interstices into which the activation material is lled. The lead wire |3c for the upper electrode is connected to the strip 50c brought back on the outside of the envelope I5c instead of ine side as in the case shown in Fig. 1.

This application is a continuation-impart of `applicants prior application Serial Number 643,502, filed November 19, 1932, and now Patent Number 2,092,363, granted September '7, 1937.

We claim: 1. An electrical discharge device which comprises a sealed tube permeable to radiation o1' the discharge, a iilling therein adapted to carry a luminous electrical discharge, electrodes positioned at opposite ends of the tube at least one of which is an activated electrode adapted to be heated to a 4glowing temperature by action of lthe discharge itself, electrode support wires sealed through the tube at the same end thereof beyond the electrode, the longer of said wires extending along the path of the discharge near the side of the tube and to the electrode at the .opposite end of the tube, an insulating tube on said longer .support wire adapted to insulate it from the discharge and the other electrode, a connector base havingpcontact members connected to said electrode support wires, a tubular member extending between said tube and the base adapted to restrict heat transfer therebetween and forming a substantially rigid mechanical connection between the tube and the base, the tubular connection member comprising a metallic sleeve around the end of the tube electrically connected to one of the electrode support wires, and the device further including a conductive layer on thesurface of the tube beneath said metallic sleeve and electrically connected to the other electrode support wire, and a layer of insulating material between said conductive layer and said sleeve whereby to provide a 'capacity in parallel with the discharge to faeuitate starting. l

2. In an electrical discharge device a sealed tube, a filling in the tube adapted to provide a gaseous pressure at operating temperature Sufciently high so that the discharge takes the form of an intense luminous cord constricted from the wall of the tube, electrodes positioned at opposite ends of the tube at least one of which is an activated electrode adapted to be heated to arcing temperature by the discharge, lead-in wires for the electrodes sealed through one end of the tube beyond one of said electrodes including a shorter wire connected to the nearer electrode and a single longer wire extended near the wall of the tube to the opposite electrode and an insulating tube on said longer wire adapted to insulate it from the discharge and the nearer electrode, and said electrodes being positioned so that the portions thereof from which the discharge emanates are eccentric within the tube, the support wire passing along the opposite side of the tube.

3. In an electrical discharge device a sealedtube, a lling in the tube adapted to provide a gaseous pressure at operating temperature sufciently high so that the discharge takes the form of an intense luminous cord constricted from the wall of the tube, electrodes positioned at opposite ends of the tube at least one of which is an activated electrode adapted t0 be heated to arcing temperature by the discharge, lead-in wires yfor the electrodes sealed through one end of the tube beyond one of said electrodes including a shorter wire connected to the nearer electrode and a single longer wire extended near the wall of the tube to the opposite electrode and an insulating tube on said longer wire adapted to insulate it from the discharge and the nearer electrode, and said electrodes being positioned so that the portions thereof from which the discharge emanates are eccentric within the tube, they support wire passing along the opposite side of the tube, and the tube being bulged outwardly between the electrode at least on the side along which the support wire being bent portion.

4. In an electrical discharge device of the type having a sealed tube, electrodes positioned at opposite ends thereof. at least one of which is an activated electrode adapted to be heated to glowing temperature by action of the discharge itself, and :filling material adapted to provide a outward along said bulged bination therewith of a capacitymember on at least one end of the tube, connected to one o1' the electrodes and comprising a conductive layer substantially covering the end of the tube surrounding an electrode, which combination further includes a' connector base and the capacity member includes a metal mounting by which the discharge tube is secured to the connector base.

5. In an electrical discharge device of the type having a sealed tube, electrodes positioned at opposite ends thereof, at least one of which is -an activated electrode adapted to be heated to glowing temperature by action of the discharge itself, lling material adapted to provide a gaseous atmosphere for the discharge, and means for supplying current to the discharge adapted to raise the tube to a temperature at which it is capable of injury by a vonage 1ess than the maximum available from the current supplying means when no current is owing, the combination therewith of a solid current carrying member electrically connected to one of said Wire passes and the support electrodes and substantially in contact with the outside of said sealed tube, and a conductive film in substantially complete contact with the surface of said tube beneath said current carrying membenwhereby to distribute the charge of said current carrying member Iover a sub- .stantial area and avoid concentration thereof at points of contact between the tube and said member.

6. In an electrical discharge device of the type having a sealed tube, electrodes positioned at opposite ends thereof and lling material in the tube adapted to provide a gaseous atmosphere for the discharge and comprising a vaporizable material the vapor pressure of which affects the nature of the discharge in the device and which may strike, whereby substantially to fix the posirequires the maintenance of a high super- 4 y tube. i

7. In an electrical discharge device of the type having a sealed tube, electrodes positioned at opposite ends thereof and filling material in the tube adapted to provide a gaseous atmosphere for the discharge and comprising a vaporizable material the vapor pressure of which affects the nature of the discharge in the device and which requires the maintenance of a high superatmospheric temperature for the intended operation of the device the combination therewith of a connector base and mounting means secured to the base at one end and engaging the sealed tube at a substantial distance from said base and adapted to support said tube from the base and to restrict heat transfer between said tube and the base, said mounting means comprising a tubular member secured at one end to the connector base and surrounding the end of the sealed tube, means between the tubular member and said sealed tube for holding' the tube spaced from the tubular member, and means between the tube and the tubular member for intercepting heat transfer from the tube to said mounting.

8. In an electrical discharge device of the type having .a sealed tube, electrodes positioned at oppositeends thereof and lling material in the tube adapted to provide a gaseous atmosphere for the discharge and comprising a vaporizable material the vapor pressure of which aects the nature of the discharge in the device and which requires the -maintenance of a high superatmospheric temperature for the intended operation of the device the combination therewith of a connector base and mounting means secured to the base at one end and engaging the sealed tube at a substantial distance from said base and adapted to support said tube from the base and to restrict heat transfer between said tube and the base, said mounting means comprising a tubular member secured at one end to the connector base and surounding the end of the sealed tube, a layer of thermal insulation `material between the tube and the tubular mounting member, and a heat reflecting layer between said tube and said thermal insulation material.

. whereby to repel the discharge from said Wall.

9. A high pressure arc discharge lamp designed for operation from a source of current of y predetermined potential and current capacity which operates with an intense luminous cord constricted with respect to the cross-sectionalarea of the envelope, and which has a tubular glass Aenvelope permeable to at least part of the radiation from the discharge, a filling of vaporizable material adapted to provide during normal operation a gaseous atmosphere for the arc at high pressure adapted to give said constricted cord, solid electrodes at least one of which is activated, having limited area on which the arc tion .of the arc, which is characterized by the positioning of said electrodes eccentrically of said envelope and the proportioning of the envelope so that, when operating from said current source in horizontal position with'said limited arcing areas of the electrodes below the axis f of the tube the arccord willnot impinge against the uppermost wall, and when operating vertically on said current source the arc cord will not impinge against the opposite wall.

10. An arc discharge device comprising a sealed tube, electrodes spaced apart in said tube and a v lling therein adapted to provide a discharge carrying atmosphere of pressure suii'iciently high to give a constricted luminous cord discharge substantially narrower than the inside diameter of the tube, means for supplying current for the discharge sunicient to cause injury to a wall of the tube if the discharge cord burns too close to said wall and, means for conducting the entire current for the discharge along said wall in a direction opposite to its flow in the discharge,

by the opposed electro-magnetic effects of the current flowing in opposite directions through the arc and said conducting means respectively, said electrodes being positioned with the arccarrying portions thereof eccentrically in said tube on the opposite side of its axis from said current conducting means, and the tube being so shaped anddimensioned that when it is positioned vertically with the arc burning therein from said current source the wall opposite said current conducting means is substantially spaced from the luminous cord of the discharge.

11. vAn electrical discharge device comprising a source of alternating current, a sealed tube, a filling in said tube of material adapted to pro- .vide a gaseous atmosphere for the discharge,

to the electrodes, a capacity between the electrodes including a conductive member secured to said tube in capacitative relation to the curren-t conducting means to one electrode and connected to the electrode, an inductance in series between said current source and said current conducting means which with said capacity is not resonantto the frequency of the alternating current source, additional capacity adapted when connected into the circuit with said electrodes, said first-named capacity and said inductance to produce resonance, and means for connecting said second-named capacity into the `circuit for starting and disconnecting it therefrom when the discharge has started.

12. An electrical discharge device'comprlsing a source of current, a sealed tube.r` a lling in said tube of material adapted to provide a gaseous atmosphere lfor the discharge electrodes positioned at opposite ends of the tube. means for -an auxiliary electrode near to one electrode so as to provide a shorter discharge path and connected into the discharge circuit through an impedance so that the discharge therefrom will be short circuited by a discharge between the principal electrodes when the discharge is established in the path between the principal electrodes, means for conducting the discharge current to the electrodes, a capacity in parallel across said discharge paths, electrodes, and ballasting im pedance in series with said discharge paths, the capacity and the impedance being proportioned to give relaxation oscillations with the auxiliary discharge and resonance to some frequency produced by the oscillations, whereby to establish the discharge between the principal electrodes. 14. A device as deilned in claim 13 in which the current source is an alternating current source, the impedance is an inductance, and the circuit is in resonance at a higher harmonic of the frequency of the alternating .current from said source which harmonic is produced by the relaxation oscillation. I

15. An electric gaseous discharge device comprising a tubular sealed envelope having a vaporizable material therein, a plurality of inleads sealed into one end oi' said envelope and supporting electrodes therein, a sleeve secured to said end of said envelope and enclosing said inleads, and a base secured to said sleeve and connected to said inleads, said sleeve including an intermediate portion between the base and end of the lamp of lesser heat conductivity than the base and the remainder of the sleeve to maintain'the end of the envelope at a temperature sufficient to prevent condensation of said vaporizable material thereon. Y

16. An arc discharge device comprising a source of limited current from the discharge, a sealed tube, electrodes spaced apart in said tube, and a lling therein adapted to provide a discharge carrying atmosphere of pressure sufcientlyhigh to produce'a constricted luminous cord discharge substantially narrower thanl the inside diameter of the tube, said current source supplying suiicient current for the discharge to cause injury to a wall of the tube it the discharge cord shifts its position tooclose to said wall and a conductor for the current to one electrode which extends along said wall of the tube beside the discharge path whereby to hold the discharge away from the tube by the opposed electro-magnetic eects of the current owing in opposite directions through the arc and said conductor respectively, the current source, the distance between the electrodes and the distance from the wall subject to injury, measured midway between the electrodes, to the axis connecting the parts of said electrodes on which the arc strikes being proportioned respectively so that said distance between the axis and the part of the wall subject to injury is greater than the distance between the electrodes divided by the amperage of the current derived from said current source.

17. An arc discharge device comprising` a source of limited current'from the discharge, a sealed tube, electrodes spaced apart in said tube. and a lling therein adapted to provide a discharge carrying atmosphere of pressure sufciently high to produce a constricted luminous cord discharge substantially narrower than the inside diameter of the tube, said current source supplying suflicient current for the discharge to cause injury to a wall of the tube if the discharge cord shifts its position .too close to said wall and a conductor for the current toone electrode which extends along said wall of the tube beside the dischargepath whereby to holdv the discharge away from the tube by the opposed electro-magnetic effects of the current owing in opposite directions through the arc and said conductor respectively, the current source, the distance between the electrodes and the distance from the wall subject to injury, measured midway between the electrodes, to the axis connecting the parts of said electrodes on which the arc strikes being proportioned respectively so that said distance between the axis and the part of the Wall subject to injury is approximately vone and one-half times the distance between the electrodes divided by the amperage of the current derived from said current source.

HANS J. SPANNER. WERNER LUCAS. 

